Suspension device for magnetic transducers

ABSTRACT

A suspension device is disclosed which is formed from a single thickness of resilient material for urging a plurality of magnetic heads toward a moving magnetic surface. The suspension device comprises a base area adapted to be affixed to a support structure, a plurality of adjacent gimbal sets each having a first sinuous gimbal member and a second sinuous gimbal member, and a plurality of leaf spring members that join the gimbal sets to the base area. The sinuous gimbal members each further comprise a plurality of laterally adjacent gimbal legs.

This invention relates generally to magnetic disc recording systems andmore particularly to a suspension spring device for supporting aplurality of magnetic heads against a moving magnetic disc surface.

Reference is made to the following co-pending applications concurrentlyfiled with this application: Ser. No. 44,535, filed June 1, 1979 andentitled "Actuator Apparatus for Magnetic Disc Recording Systems"; Ser.No. 44,533, filed June 1, 1979 and entitled "Gas Circulation andFiltration Apparatus for Magnetic Disc Recording Systems"; and Ser. No.44,534, filed June 1, 1979 and entitled "Isolated Multiple Core MagneticTransducer Assembly." The above-referenced applications are assigned tothe same assignee as this application and disclose and claim subjectmatter related to the present application.

Magnetic disc recording systems commonly utilize one or more magneticheads that are urged toward a rotating magnetic disc by suspensiondevices of various designs. The magnetic heads ride against a fluidbearing formed between the magnetic heads and the rotating disc,allowing the magnetic heads to follow surface imperfections within therotating disc. Magnetic heads of this type are often referred to as"flying" heads.

In order to allow the magnetic heads to more freely ride against thefluid bearing, most suspension devices commonly used include a gimbalmeans that allows the magnetic heads freedom of rotation in two axes butrestricts rotation in a third access normal to the disc surface.Additionally, some suspension devices provide leaf springs that urge thegimbal and magnetic head against the fluid bearing.

For example, U.S. Pat. Nos. 3,581,298 and 3,582,920 disclose supportdevices formed from a single thickness of resilient material that isused to support a single magnetic head. U.S. Pat. No. 3,593,330 alsodescribes a support device formed from a single thickness of resilientmaterial that is used in combination with a second identical supportdevice to position a plurality of magnetic cores against a rotatingdisc. Support devices utilizing separate springs to urge a magnetic coreor a plurality of magnetic heads against a rotating disc are describedin U.S. Pat. Nos. 3,599,193 and 4,141,050. As can be seen, none of thedescribed suspension devices provide both gimbal support and leaf springpressure loading for a plurality of magnetic heads in one easily formedthickness of resilient material.

The device of the present invention overcomes these limitations andgenerally comprises a suspension spring that has a base member, aplurality of adjacent gimbal sets, and a plurality of leaf springmembers connecting the base area and the gimbal sets. Each gimbal setincludes a left and right sinuous gimbal member which are comprised of aplurality of laterally adjacent gimbal legs joined at alternating endsto define the sinuous form. Magnetic heads are bonded to extensionsegments that extend from the outer ends of the sinuous gimbal members.The centers of the sinuous gimbal members are joined to the leaf springmembers for urging the gimbal sets and the magnetic heads toward thesurface of a rotating disc. The gimbal sets allow the magnetic heads toride along the surface of the rotating disc but limit rotation of themagnetic heads about an axis normal to the surface of the disc.

It is thus an object of the present invention to provide an improvedmagnetic head suspension device.

It is a further object of the present invention to provide a magnetichead suspension device that is easily and inexpensively manufactured.

It is another object of the present invention to provide a magnetic headsuspension device that includes both support and spring loading.

These and other objects and advantages of the present invention will beapparent from the following description and accompanying drawings.

IN THE DRAWINGS

FIG. 1 is a block diagram of a magnetic disc recording system thatincorporates the suspension device of the present invention.

FIG. 2 is a side view of the actuator assembly.

FIG. 3 is an end view of the actuator assembly.

FIG. 4 is a view of the actuator assembly as taken substantially throughlines 4--4 of FIGS. 2 and 3.

FIG. 5 is a view of a magnetic head, the suspension device and theparallelogram as taken substantially through lines 5--5 of FIG. 4.

FIG. 6 is a top view of the suspension device prior to forming theextension segments and pads.

FIGS. 7a and 7b are enlarged views of portions of a suspension devicegimbal set.

FIG. 8 shows the suspension device after forming the exterior segmentsand pads.

DETAILED DESCRIPTION OF THE INVENTION

Referring first to FIG. 1, a magnetic disc system incorporating oneembodiment of the actuator of the present invention is shown therein insubstantially block diagram form. A rigid disc 10, coated on at leastone side with a suitable magnetically active material is supported atand rotated about its central axis by a drive means 11. A plurality ofmagnetic heads 12, mounted on and supported by an actuator apparatus 13,are positioned near the magnetically susceptible portion of the disc 10,for example, beneath the disc 10.

The drive means 11 rotates the disc 10 at a rate of, for example, 3600rpm, thereby moving the disc 10 past the heads 12. In this mannerinformation supplied to the heads 12 may be recorded on that portion ofthe magnetic disc which passes under the heads 12; conversely,information previously stored on the portion of the disc 10 passingunder the heads 12 may be retrieved, or read, from the disc 10. Theportion of the disc 10 passing under a single one of the heads 12 iscommonly referred to as one track; a conventional disc 10 may have asmany as one-hundred sixty tracks.

To permit all of the storage area on the disc to be utilized, it isnecessary to move the heads 12 across the disc 10. To accomplish this,an electronic control device 14 supplies signals to the actuatorapparatus 13 which causes the magnetic heads 12 to be moved transverselyacross the disc along a path which is substantially a radius of the disc10, thereby repositioning the heads 12 under different tracks of thedisc 10.

With reference now to FIG. 2, the magnetic recording rigid disc 10,coated on a least one side with a suitable magnetically active material16, is clamped at its center by hub 17 which may, for example, bemounted to the shaft of motor 18. The motor 18, when energized, causesthe disc 10 to rotate in the direction shown by arrow 19 (FIG. 4). Inorder to record magnetic information onto the surface of disc 10 or torecover magnetic information from the surface of disc 10, the actuatorapparatus generally designated 13 positions magnetic heads 21a-e nearthe magnetically active material of disc 10 by means of a suspensionspring 50. The suspension spring 50 is supported by a parallelogramshaped supporting strucure 120 which includes an inner member 122affixed to an actuator base plate 130 and an outer member 121 that isresiliently attached to the inner member 122 by two flat springs 123 and124. The actuator base plate 130 also supports a stepper motor 141 and adrive band 220. The drive band 220 is clamped to the outer member 121 bya clamp 223 and is connected to the shaft 157 (FIG. 3) of the steppermotor 141 by a drive hub 160. The drive hub 160 transfers 130 therotational displacement of the shaft 157 to the drive band 220 whichconverts this movement into a linear displacement that is coupled to theouter member 121, the suspension spring 50, and the magnetic heads 21a-e(FIG. 4) A detailed understanding of the actuator apparatus 13 will beobtained through the description that follows.

The magnetic heads 21a-e (FIG. 2) are used to record and recovermagnetic information from the surface of disc 10. The magnetic heads arepreferably of the Winchester type, that is, a low-mass magnetic headthat is separated from the disc during operation by a fluid bearingproduced as a result of the disc rotation. An exemplary magnetic headhas four magnetic cores 30 through 33 with a nominal center-to-centercore separation distance equal to eight times the center-to-centerdistance between two adjacent tracks of information recorded on disc 10,or by way of example, the nominal center-to-center distance between ninetracks of information. Co-pending application Ser. No. 44,534 filed June1, 1979 describes such an exemplary magnetic head.

As shown in FIG. 5, notch 34 is formed into the magnetic head 21 andeach core 30-33 has a gap 37. Magnetizing coils 36 are individuallywound around cores 30 through 33 and are connected to a switching board38 which contains the necessary switching circuitry for selecting theone core out of the twenty cores contained on magnetic heads 21a-e thatwill be active during a given read or write operation. The switchingcircuitry may utilize, for example, switching diodes to achieve thedesired selection.

The suspension spring 50, shown generaly in FIG. 2 and illustrated indetail in FIG. 6, comprises a plurality of primary members designatedtypically at 52 and a plurality of secondary members 53 that connect atone end to spring base area 51. Approximately halfway along the lengthof secondary members 53, inner cross-members 54 join an outer pair ofsecondary members 53 to a single inner primary member 52 at anintersection 56. The suspension spring 50 may be formed by a suitableprocess, such as etching, from a resilient material which may bephosphor bronze or other suitable material.

The primary member 52, as better seen in FIG. 7, extends beyondintersection 56 and is split to form a right serpentine gimbal and aleft serpentine gimbal, generally designated 57a and 57b, respectively.The right serpentine gimbal 57a is formed by first through fifthserpentine gimbal legs 59 through 63 respectively, wherein the first,third and fifth gimbal legs 59, 61, and 63 lie generally parallel to theaxis of primary and secondary members 52 and 53, and second and fourthgimbal legs 60 and 62 lie substantially parallel to inner cross-member54 and perpendicular to primary and secondary members 52 and 53. One endof second gimbal leg 60 connects to an end of the first gimbal leg 59and the remaining end of second gimbal leg 60 connects to a first and ofthird leg 61. A first end of fourth gimbal leg 62 connects to theremaining end of third gimbal leg 61. The remaining end of fourth gimballeg 62 connects to a first end of the fifth gimbal leg 63. The secondand fourth gimbal legs 60 and 62 are substantially shorter than thefirst, third and fifth gimbal legs 59, 61 and 63 so as to form agenerally compressed serpentine design.

The remaining end of the fifth gimbal leg 63 is attached to an extensionsegment 64 which is in turn attached to a pad 65. Between the fifthgimbal leg 63 and the extension segment 64 are formed notches 66 and 67at each edge of the extension segment 64 and fifth gimbal leg 63.Similarly, between the extension segment 64 and pad 65 and at each edgeof segment 64 and pad 65, are formed notches 68 and 69. Notches 66 and67 define a boundary between fifth gimbal leg 63 and extension segment64, and notches 68 and 69 define a boundary between extension segment 64and pad 65. The purpose of the boundaries will be explained below withthe reference to FIG. 8. The width of pad 65 is substantially wider thanextension segment 64 or fifth gimbal leg 63, so as so as to better bondpad 65 to magnetic transducer 21a as will be made clear hereinafter infurther discussion of FIG. 5.

The notch 70 is formed at the outer corner of pad 65. The notches 66-69are generally triangular in shape while notch 70 is generallyrectangular in shape. A groove 71, having a curved cross section asshown in the enlarged side view of FIG. 7, is preferably formed in theextension segment 64. The groove 71 may be suitably formed by exposingthe grooved portion of extension segment 64 to the etching solutionduring the last stages of the formation of suspension spring 50.

Left serpentine gimbal 57b (FIG. 7) is a mirror image of rightserpentine gimbal 57a and is otherwise identical to right serpentinegimbal 57a in detail. Four additional sets of right and left serpentinegimbals 80 through 83 (FIG. 6) are etched into suspension spring 50,each set being formed at one end of a primary member 52. Each secondarymember 53 extends beyond second gimbal leg 60 and all secondary members53 are joined together by five outer cross-members 55. Each gimbal set80 through 84 is thus enclosed in an area defined by inner cross member543, secondary members 53 and outer cross-members 55.

Circular holes 90 through 94 (FIG. 6) are formed into spring base area51 substantially on the center lines of primary members 52. In apreferred embodiment, the primary members 52 and secondary members 53are smoothly joined by the spring base area 51 to form a radius 100.Similarly, the primary members 52 and secondary members 53 are smoothlyjoined on either side of the inner cross-member 54 to form radii 101 and102, respectively. Another radius 103 provides a smooth junction betweenthe secondary members 53 and the outer cross-member 55, while a radius104 (better seen in FIG. 7) is formed to join the primary members 52 tothe first gimbal legs 59 and 72. The first, second and third gimbal legs59-61 are joined in a similar manner by a radius 105, while a radius 106results from the junction of the third, fourth and fifth gimbal legs61-63.

After the etching process is completed to form the suspension spring 50as shown in FIG. 7, each of the extension segments 64 is bent at thenotches therein to form an angle as better shown in FIG. 8. Moreparticularly, the extension segments 64 are bent downward along theboundary defined by notches 66 and 67 to form a ninety degreeangle-between the extension segment 64 and the gimbal legs 61, 62 and63. The pads 65 are then bent ninety degrees at the boundary defined bynotches 68 and 69 to cause the pads to form a plane which issubstantially parallel to the plane defined by the body of thesuspension spring 50, and spaced therefrom at a distance equal to thedistance between the boundaries defined by the notches 66-67 and 68-69.FIG. 8 thus illustrates one completely formed extension segment 64 andpad 65, with the remaining pads and extension segments of the suspensionspring 50 being substantially identical.

Once the suspension spring 50 is completed, the magnetic heads 21a-e aremounted on the pads 65 thereof. More specifically, each of the magneticheads 21a-e is aligned such that the gaps 37 are perpendicular to theaxis of first gimbal legs 59 and 72, and is then positioned such thatthe cores 30-33 and the trailing edge 39 of the heads 21a-e are nearestthe downstream side 115 of the extension segments 64. When thisorientation is achieved, the pads 65 are bonded to the notches 34 in themagnetic heads 21a-e in any conventional manner. To ensure precisealignment among all of the magnetic heads 21a-e, the heads arepreferably simultaneously aligned in a jig while being bonded. As theresult of such alignment, the distances between any two adjacent coresis equal, whether on the same head or on adjacent heads, with thenominal center-to-center spacing between adjacent cores being, forexample, the nominal center-to-center spacing between nine tracks ofinformation on the disc 10.

With respect to FIG. 4, the actuator base plate 130 comprises a platemember 131 preferably formed integrally with a support member 132 and aneccentric pulley mounting arm 133. The plate member 131 is preferablyrectangular or square in shape and the support member 132 extends in asubstantially orthogonal manner from the center of one edge of the platemember 131. The eccentric pulley mounting arm 133 extends substantiallyperpendicular to the support member 132, thereby cooperating with theplate member 131 and support member 132 to define a rectangular area134. One wall 135 of the rectangular area 134 is formed by a side of theeccentric pulley mounting arm 133. A second and opposite wall 136 ofarea 134 is similarly formed by a side of the support member 132. Thelonger dimension of rectangular area 134 is determined by parallelogramsupport member 132 and the wall 137.

A parallelogram shaped supporting structure 120, best seen in FIG. 4, isdisposed within the rectangular area 134 and comprises an inner member122, a pair of spring members 123 and 124 connected thereto, and anouter member 121 affixed to the ends of the spring members 123 and 124,which may be flat. The spring members 123 and 124 which preferablyextend substantially orthogonal to both the inner member 122 and theouter member 121, may be affixed thereto by any suitable means such asbrazing or welding. The inner member 122, which may for example have asolid square cross-section, is affixed to the wall 137 of the supportmember 132. The outer member 121 may have, for example, a substantiallysquare tubular cross-section as seen in FIG. 5, with one flat outer edge127 generally parallel to one surface of the actuator base plate 130.

One side of base area 51 of suspension spring 50 is mounted to flatsurface 127 and the opposite side of spring base area 51 and suspensionspring 50 is adjacent to the disc 10. The extension segment 64 of FIG. 8and the pad 65 thus extend from the side of suspension spring 50 that isadjacent to disc 10. The pad pairs 65 of each gimbal set 80-84 urge themagnetic heads 21a-e toward the fluid bearing surface of the disc 10.Sufficient clearance (FIG. 4) between the walls 135 and 136 of therectangular area 134 and the spring members 123 and 124, respectively,is provided so that parallelorgram outer member 121 is free to movesuspension spring 50 and magnetic heads 21a-e through a distance equalto at least the distance between eight tracks of magnetic informationstored on disc 10.

The stepper motor 141 (FIG. 3) is mounted to the actuator base plate 130by means of four screws 143 and nuts 150 or other suitable means. Astepper motor cylindrical case 140 fits through a notched circular hole142 that is formed into the actuator base plate 130, and a stepper motorsquare mounting flange 154 fits within a recess defined by the surfaces155 and 156 of the actuator base plate 130 (FIG. 2). The stepper motorshaft 157 protrudes from the same side of stepper motor 141 as themounting flange 154 and is generally perpendicular to actuator baseplate surface 155. The shaft 157 extends away from a plane defined bydisc 10. An exemplary stepper motor is model number SM40-480manufactured by Fuji of Japan and available through Rock Associates ofBuena Park, Calif.

A drive hub 160 (FIG. 3) is attached to the stepper motor shaft 157 bymeans of pin 161 that passes radially through hub 160 and extends into acorresponding hole formed into shaft 157. The drive hub 160 is formed toinclude a first and smaller diameter hub 162 nearest stepper motor 141on shaft 157, and a second and larger diameter hub 163 farther fromstepper motor 141. A stop arm 170, having, for example, a solid circularcross-section, is attached to the larger hub 163 and extends radiallyfrom the shaft 157. Stop plate 171 which may be formed from suitableL-shaped angle stock and which is secured to actuator base plate surface155 includes a first leg 177 that is formed at a right angle to thesecond leg 178. The second leg 178, which extends perpendicular toactuator base plate 130, includes a rectangular cut out area 176 (FIG.4) defined by a first end stop 173, a second end stop 174 and an edge175. The stop arm 170, which extends radially from the shaft 157 andpasses through the rectangular cut out area 176, moves between first endstop 113 and second end stop 174 in accordance with the rotation of theshaft 157. Further movement of stop arm 170 is restricted when the stoparm 170 abuts either first end stop 173 or second end stop 174, thuslimiting the angle of rotation through which shaft 157 may travel.Attached to a second end of stop arm 170 and extending coaxiallytherefrom is flag 180 formed from a suitable flat, stiff material, suchas opaque plastic, and affixed generally parallel to the plane of thedisc 10.

A generally U-shaped optical detector 182 (FIG. 3), such as a type OPB804 manufactured by Optron, Inc. is attached to actuator base plate 130by means of bracket 185 and is positioned with the U-shape of opticaldetector 182 opening toward stepper motor 141. Optical detector 182 hasa light source 183 in a first leg of the U and a detector 184 in thesecond leg. When the shaft 157 has rotated stop arm 170 to be proximateto the first end stop 173, the flag 180 is disposed within the U-shapedoptical detector 182, interrupting the light detected by detector 184from source 183 and thus providing a signal from detector 184 which maybe used by the electronic means 14 to establish a zero or home positionfor shaft 157 for use in subsequent control of the stepper motor 141.

Continuing with the description of the actuator apparatus 13 as shown inFIG. 2, a cylindrical pulley shaft base 190 is secured by a set screw192 into a correspondingly cylindrical hole 191 that is formed into theactuator base plate 130. Extending coxially from the pulley shaft base190 is a pulley shaft 193 which is substantially parallel to the shaft157. The pulley 194 is disposed concentrically over the shaft 193 and isretained by a clip spring 195 so as to freely rotate about the shaft193. Similarly, the cylindrical shaft base 200 is secured by means of aset screw 201 within correspondingly cylindrical hole 202 formed intothe actuator base plate 130. An annular groove 209 formed into thepulley shaft base 200 receives an end of the set screw 201 to positionthe pulley shaft base 200 within the actuator base plate 130. A hole 203is formed off-center within the pulley shaft base 200. A pulley shaft204 is affixed within the hole 203 and extends from the shaft base 200.A groove 205 is formed across a diameter of the pulley shaft base 200 ina side of the shaft base 200 opposite the extension of the pulley shaft204. A pulley 206 is disposed over the pulley shaft 204 and held inplace by a clip spring 207 so as to rotate freely about the pulley shaft204. A line 208 (FIG. 4) drawn between the outer surface of the pulley194 and the pulley 206 is substantially parallel to the outer member121.

A drive band 220 (FIG. 2) is formed from a suitably inelastic butflexible material such as 0.0015-inch thick grade 302 stainless steel.The drive band 220 has overlapping ends that are welded or bonded toform a continuous loop around the circumferences of the smaller hub 162and pulleys 194 and 206. End flanges 196, 197, 210 and 211 of thepulleys 194 and 206 support the drive band 220, thus centering andretaining drive band 220 upon the pulleys 194 and 206. A pin 221 (FIG.3) is affixed to smaller hub 162 and engages an orifice 222 formed intodrive band 220 to positively couple the rotational movement of the shaft157 and the smaller hub 162 to the drive band 220, thereby convertingthe rotational movement of the shaft 157 into a linear displacement ofthe drive band 220.

A first portion 224 (FIG. 4) of a clip 223 is affixed to the side wallof the parallelogram outer member 121 that is within the interior region134 generally defined by the supporting structure 120 and extendstherefrom generally perpendicular to and away from disc 10. Theextension of a first portion 224 contacts the outer surface of driveband 220. A second portion 225 of the clip 223 is disposed adjacent tothe inner surface of the drive band 220 and is secured to the firstportion 224, thereby clamping the drive band 220 to the outer member 121and transferring any linear displacement of the drive band 220 generallyalong the line 208 to the outer member 121.

To ensure proper positioning of the heads with respect to the rotationof the shaft 157, the tension on the drive band may be adjusted.Referring to FIG. 2, to adjust the tension on drive band 220, set screw201 is loosened and pulley shaft base 200 is rotated within actuatorbase plate 130 by means of, for example, a blade screwdriver thatengages the groove 205. As the pulley shaft base 200 is rotated, thepulley shaft 204 affixed in eccentrically located hole 203 and thepulley 206 move in a circular path defiend by the axis of theeccentrically located hole 203, thereby effectively changing the overallpath length defined by the smaller hub 162, pulley 194 and pulley 206.Since the drive band 220 is of a fixed length, the rotation of thepulley shaft base 200 will serve to adjust the tension in the drive band220. Once a suitable tension is achieved, the set screw 201 is tightenedinto the annular groove 209, securing the pulley shaft base 200.

Rotational means 15, as shown in the block diagram of FIG. 1, mayinclude a solenoid or a gear drive means affixed to mounting plate 232(FIG. 3) that supports actuator base plate 130 along an axis 230 (FIG.4) to position magnetic heads 21a-e against disc 10 while disc 10rotates. The solenoid or gear drive means then rotates actuator baseplate 130 in the direction of arrow 231 (FIG. 3) when disc 10 ceasesrotation. This rotational displacement is sufficient to withdrawmagnetic heads 21a-e from their operational position near the surface ofdisc 10. If the rotational means 15 are not provided, the highlypolished surface of disc 10 may bond to the similarly highly polishedfluid bearing surface 35 (FIG. 5) of magnetic heads 21a-e when disc 10is not rotating; furthermore, the magnetically active material 11 may beworn away from the surface of disc 10 if magnetic heads 21a-e vibratewhile at rest against disc 10 as may occur, for example, during theshipping or moving of a completed disc drive system employing theabove-described actuator apparatus 13.

The operation of the above-described actuator apparatus 13 will now bedescribed. During operation of the actuator apparatus 13, the actuatorbase plate 130 is positioned, by the rotational means 15 describedabove, substantially parallel to disc 10, thus urging magnetic heads21a-e toward the surface of disc 10.

During operation of a magnetic disc system incorporating the actuator ofthe present invention, as shown in FIG. 1, the plate 130 is positioned,by the rotational means 15 described above, substantially parallel tothe disc 10, thus urging the magnetic heads 21a-e toward the surface ofthe disc 10. Due to the equilibrium which results between the suspensionspring 50 (which urges the heads toward the disc surface) and the fluidbearing (which forms due to the aerodynamics of the heads 21a-e and therelative motion imparted between the disc 10 and heads 21a-e), the lowmass flying heads 21a-e do not touch the surface of the disc but insteadclosely follow the contours of the disc. The thickness of the fluidbearing, or the distance from the disc 10 to the head 21a-e, decreasesas the force of the suspension spring increases.

Control signals are provided to stepper motor 141 through connectingwires 239 from an electronic control device 14 as described with regardto FIG. 1 above. The control signals energizes the stepper motor 141,causing it to rotate the shaft 157, drive hub 160, stop arm 170 and flag180 one angular position or "step" at a time to one of eight angularpositions. The first such angular position 241 is achieved when the stoparm 170 is adjacent to the first end stop 173 and flag 180 is disposedwithin the optical detector 182. The eight angular position 248 isachieved when the stop arm 170 is adjacent to second end stop 174. Theremaining angular positions 242 through 247, respectively, eachrepresent one "step" of stepper motor 141 and the angular displacementbetween each angular position 242 through 248 is essentially equal.

The drive band 220 (FIG. 4) translates the angular displacement ofsmaller hub 162 into a corresponding linear displacement which is aresult of the angular displacement and diameter of the smaller hub 162.The linear displacement of the drive band 220 is coupled through theclip 223 to the parallelogram outer member 121, which is relatively freeto move at the ends of the flat springs 123 and 124 in a path thatremains essentially parallel to the parallelogram inner member 122. Theparallelogram outer member 121 and parallelogram inner member 122 arepositioned by the actuator baseplate 130 to be parallel to a radius 250of disc 10 and thus the outer member 121 moves along a path that isessentially parallel to a radius 250. The displacement of the outermember 121 along this parallel path is equal to the linear displacementof the drive band 220 as coupled to the outer member 121 through theclip 223. In this manner the eight angular positions 240 through 248 aretranslated into eight positions of the outer member 121 parallel toradius 250, with the first angular position 241 corresponding to aposition of the outer member 121 nearest the pulley 194 and the eighthangular position 248 corresponding to a position of the outer member 121nearest the pulley 204.

The positions assumed by the parallelogram outer member 121 aretransferred to the suspension spring 50 that is affixed to the outermember 121. These positions in turn are transferred to the magneticheads 21a-e. The distance between each adjacent position assumed by theouter member 121 is equal to the nominal center-to-center distancebetween two adjacent tracks of information stored on the surface of disc10. As described above, the nominal center-to-center distance betweenadjacent magnetic cores shown typically at 30 through 33 is equal to thenominal center-to-center distance between nine tracks of informationrecorded on disc 10. Thus, as outer member 121 is moved through itsrange of eight positions, the twenty magnetic cores on magnetic heads21a-e will be moved across 160 tracks of recorded information on disc 10in groups of 20 tracks per position.

For example, when the stepper motor 141 is adjusted to assume the firstangular position 241, the magnetic core 30 of magnetic head 21a will bepositioned over the first track of magnetic information nearest theouter edge of disc 10, the magnetic core 31 will be positioned over theninth track of magnetic information, and so on. If stepper motor 141 isadjusted to angular position 242, magnetic cores 30 and 31 will be movedtoward the center of disc 10, coming to rest over the second and tenthtracks of recorded information. As stepper motor 141 is stepped throughremaining angular positions 243-248, magnetic cores 30 and 31 will bepositioned over the third through the eighth and the eleventh throughthe sixteenth tracks, respectively. The remaining magnetic cores will besimilarly positioned over a total of 160 tracks.

The right serpentine gimbal 57a and left serpentine gimbal 57b of thefirst gimbal set 84 (FIGS. 7 and 8) provide the gimbal 58 of firstgimbal set 84 (FIGS. 5 and 6) provide the gimbal movement required bymagnetic head 21a so that the magnetic head 21a will remain aligned withthe tracks of information on the surface of the disc 10. By way ofexample, the pad 65 of the right serpentine gimbal 57a may be movedtoward or away from the surface of the disc 10 (FIG. 5) by flexing firstthrough fifth gimbal legs 59-63; pad 65 (FIGS. 7 and 8) may also berotated substantially freely about an axis parallel to a radius of thedisc 10 and parallel to the surface of the disc 10 by primarily flexingthe extension segment 64. The groove 71 formed into the extensionsegment 64 aids this flexing motion. As described above, the magnetichead 21a is bonded to and supported by pads 65 of right serpentinegimbal 57a and left serpentine gimbal 57b, respectively. As the magnetichead 21 a is urged against the disc 10 by the suspension spring 50, theright and left serpentine gimbals 57 and 58 of the first gimbal set 84will allow the magnetic head 21a to rotate about an axis parallel to thesurface of disc 10, that is, to "roll" from side to side. Right and leftserpentine gimbals 57 and 58 will further allow the magnetic head 21 torotate about an axis that is parallel to a radius of the disc 10 andparallel to the surface of the disc 10, that is, to "pitch." Thesemovements allow the magnetic head 21a to ride on the fluid bearing overimperfections in the surface of the disc 120. However, right and leftserpentine gimbals 57a and 57b will restrict the motion of the magnetichead 21a about an axis that is normal to the surface of the disc 10,that is, to "yaw." This yaw movement must be restricted so that the gaps37 of the magnetic heads 21a-e will remain aligned with the informationtracks on the surface of the disc 10. Gimbal sets 80 through 83 (FIG. 6)function as does gimbal set 84. Thus, suspension spring 50 provides thenecessary pressure loading means and the gimbal support means requiredto properly suspend magnetic heads 21e against the rotating disc 10.

Having thus described one embodiment of my invention in detail, it is tobe understood that numerous equivalends and alterations which do notdepart from the invention will be apparent to those skilled in the art,given the teaching herein. Thus, my invention is not to be limited tothe above description but is to be of the full scope of the appendedclaims.

I claim:
 1. A suspension device for supporting a plurality of adjacentmagnetic heads against a fluid bearing formed between said magneticheads and a moving magnetic surface, comprising:a body member with anaxis parallel to the movement of the said moving magnetic surface; and aplurality of adjacent gimbal sets each having a first sinous gimbalmember and a second sinuous gimbal member, said first and second sinuousgimbal members each comprising a plurality of laterally adjacent gimballegs parallel to said axis, each said gimbal leg having a first andsecond end, said gimbal leg first and second ends alternately joined toform said sinuous gimbal members, said first and second sinuous gimbalmembers each further having a first and inner end and a second and outerend, said first end inner ends joined in substantially close proximityto said body member, each said first and second sinuous gimbal membersfurther comprising an extension member joined at a first end to saidsecond and outer ends and extending therefrom to a bonding surface forbonding to said magnetic heads.
 2. A suspension device as in claim 1wherein said bonding surface includes a pad disposed at a second end ofsaid extension member and generally parallel to said first and secondsinuous gimbal members for abuting said magnetic heads.
 3. A suspensiondevice as in claim 1 wherein said body member comprises a base areaadapted to be affixed to support means, and a plurality of leaf springmembers joining said base area to said first and inner ends.
 4. Asuspension device as in claim 3 wherein said leaf spring members areparallel to said axis.
 5. A suspension device as in claim 1 wherein saidbody member and said gimbal sets are formed from a single thickness ofresilient material.
 6. A suspension device as in claim 1 wherein saidextension members have formed therein a groove parallel to said movingmagnetic surface and intermediate said bonding surface and said secondand outer end for increasing the flexural freedom therein.
 7. Asuspension device for supporting a plurality of adjacent magnetic headsagainst a fluid bearing formed between said magnetic heads and a movingmagnetic surface, comprising,a body member with an axis parallel to themovement of said moving magnetic surface, said body member comprising abase area adapted to be affixed to support means, and a plurality ofleaf spring members having first ends joined to said base area, andhaving second and opposite ends; and a plurality of adjacent gimbal setseach having a first sinuous gimbal member and a second sinuous gimbalmember, said first and second sinuous gimbal members each comprising aplurality of laterally adjacent gimbal legs parallel to said axis, eachsaid gimbal leg having a first and second end, said gimbal leg first andsecond ends alternately joined to form said sinuous gimbal members, saidfirst and second sinuous gimbal members each further having a first andinner end and a second and outer end, said first and inner ends joinedin substantially close proximity to said second ends of said leaf springmembers, each said first and second sinuous gimbal members furthercomprising an extension member joined at a first end to said second andouter free ends and extending therefrom to a bonding surface for bondingto said magnetic heads; and said body member and said gimbal sets areformed from a single thickness of a resilient material.
 8. A suspensiondevice as in claim 7 wherein said leaf spring members are parallel tosaid axis.
 9. A suspension device as in claim 7 wherein said extensionmembers have a groove formed therein parallel to said magnetic surfaceand intermediate said bonding surface and said second and outer ends forincreasing flexure freedom therein.
 10. A suspension device forsupporting a plurality of magnetic heads for coaction with a movingmagnetic surface comprisinga body member disposed with an axis parallelto the movement of the moving magnetic surface, at least one gimbal setsupported by said body member, at least one gimbal set having first andsecond sinuous members and each said sinuous member including aplurality of connected gimbal members, and a plurality of bonding pads,each of said first and second sinuous members being connected to abonding pad adapted for mounting at least one magnetic head thereon. 11.The suspension device of claim 10 including a plurality of said gimbalsets.
 12. The suspension device of claim 10 wherein said body memberincludes a plurality of spring members, each of said gimbal sets beingsupported on one of said spring members such that said first and secondsinuous members are disposed symmetrically with respect to theassociated spring member.
 13. The suspension device of claim 12 whereinsaid sinuous members include an extension member disposed substantiallyperpendicular to the remaining portions of said sinuous members, saidbonding pads being connected to the ends of said extension members anddisposed in a plane which is substantially parallel to the plane of saidsinuous members.
 14. The suspension device of claim 10, 11, 12, or 13wherein said body member and said gimbal sets are formed from a singlethickness of resilient material.